The present invention relates to devices and methods for vascular brachytherapy, more particularly vascular brachytherapy in conjunction with percutaneous transluminal angioplasty.
Percutaneous transluminal angioplasty (PTA) is a well known technique in which a balloon is located and expanded within a stenosed portion of a vessel. The expansion of the balloon widens the stenosed portion of the vessel to permit more normal blood flow therethrough. PTA is commonly used in, but not limited to, cardiovascular atherectomy procedures. A common problem following PTA is restenosis of the vessel. It is believed that restenosis can be significantly reduced using vascular brachytherapy (VB) following and/or in combination with PTA.
To maximize the benefits of VB, it is desired to apply a measured and uniform dosage over the entire surface area of the treated vessel. Additionally, it is desirable to minimize unwanted radiation exposure of the patient""s healthy tissues and to minimize the exposure of medical staff to radiation. Attempts to achieve these goals have met with only limited success.
An embodiment in accordance with the present invention permits the delivery of a substantially uniform radiation dose to a mammalian lumen. The device includes an inflatable balloon disposed towards the distal end of a catheter tube, a pull wire slidably disposed within the catheter tube, a radiation source connected to a distal end of the pull wire and slidably disposed within the inflatable balloon. In use, the balloon is located within a lumen (e.g. a blood vessel) and inflated such that an outer wall of the balloon contacts the inner wall of the lumen. The radiation source is configured to be approximately adjacent to an internal wall of the inflated balloon. The radiation source is then drawn across the internal wall to provide a substantially uniform and controlled dose of radiation over the entire surface of the internal wall of the lumen. A radiation shield may be provided within the inflatable balloon to shield the radiation source during insertion into the lumen. The shielded radiation source is located within the vessel, unshielded, and then drawn through the inflated balloon as described above. Preferably, the balloon includes a helical balloon to guide the radiation source around the periphery of the vessel wall.